• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.421-428
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• 2005

Dissolved air flotation (OAF) is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In this study, we investigated the effect of L/W (L; Length, W; Width) on the hydro-dynamic behavior in DAF system using CFD (Computational Fluid Dynamics) and ADV (Acoustic Doppler Velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various L/W ratio (2:1, 3:1, 4:1 and 5:1) conditions were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the factual velocity at some points in the full-scale DAF system with ADV technique. Both the simulation and the measurement results were in good accordance with each other. As the results of this study, we concluded that L/W ratio and outlet geometry play important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hands, in the ration of 3:1, the fine bubbles were more evenly distributed.

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.1-8
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• 2012

In this study, the earth pressure, displacement and strain were compared with reinforcement types at segmental retaining wall through full scale model test. The test results found that the measurement of earth pressure and displacement at wall for the fully reinforced retaining wall are different from those for the partly reinforced retaining wall. The analyses of these results would suggest that the used of geoogrid allowed the vertical earth pressure and displacement at wall to be reduced. The horizontal earth pressure in upper and lower part of wall can change with reinforcement type and earth deformation and were larger than the active and the rest pressure. Also, the lateral earth pressure and displacement of wall have a very high a correlation. It was found that the strain contour distribution of reinforcements was occurred a large strain at cental part of wall in segmental retaining wall system.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.256-261
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• 2011

In this paper, a design and an implementation of an Analog to Digital (A/D) converter are introduced for the conversion of monitored battery cell voltage in the cell voltage monitoring(CVM) system in battery management system(BMS), which is one of the key devices of ECO hybrid cars. The A/D converter in CVM system required a middle conversion speed and a high resolution, therefore, a successive approximate register(SAR) typed A/D converter with 10 bits resolution has been designed and implemented using Magna 0.6um 40V process. The measurement result which kept ${\pm}1$ LSB accuracy in the full scale range(FSR) of 5V, showed the usefulness of the SAR typed A/D converter in realizing a CVM system.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.758-766
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• 2005

This study was conducted to evaluate the effect of the transverse troughs on hydrodynamic behavior within the a certain full-scale sedimentation basin (flow rate/one basin; $10,000m^3/d$) using CFD simulation and ADV technique. In order to verify the CFD simulation, we measured the factual velocity at 36 points in the full-scale sedimentation basin, whose outlet structure is inadequate, with ADV technique. Both the CFD simulation and the ADV measurement results were in good accordance with each other. From the CFD simulation results of the existing basin, it was investigated that extreme upward flow occurs in the near of two transverse troughs. It was suspected that since the transverse troughs converted the open channel flow into the local closed pipe flow, the increased pressure in this local closed pipe flow region made the extreme upward flow. For solving this problems, it was suggested to modify transverse-typed launder into finger-typed launder and to install a longitudinal baffle in the center in this study. The CFD simulation results of all suggested amendments told us that the extreme upward flow, had occurred especially in the beneath of transverse troughs, was much less in the case of finger typed launder basin than that in the existing basin. Also, it was predicted that installing a longitudinal baffle made the fully developed flow which is more effective for sedimentation.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.11-17
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• 2005

A lot of small-scale reservoirs that is extravagant in whole country are controlled state or real condition that correct data about the practice contents is not equipped all up to now. In this study, YungNam districts that region Gyeong-Ju city reservoir is distributed much of when flow speedily choose 23 peace among 73 small scale reservoir and experimented. Acquired data every 5 seconds, and user E/S and user value TS for orthocenter to 1 second interval and executes present condition measurement using RTK-GPS. Could was wave and state that reservoir of 15 places (about 65%) gives protective care that do 3D modelling with acquired data, and now correct contents about reservoir state past through comparative analysis with data. Also, area of full water and wave that analyze effective storage and area of full water of 23 places reservoir could know that 20.63%, effective storage decreased as 3.34%. I wish to contribute about analysis about present reservoir state through this and method the adminstration direction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1217-1223
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• 2003

Nerve gas sensor based on tin oxide was fabricated and its characteristics were examined. Target gas is dimethyl methyl phosphonate(C$_3$ $H_{9}$ $O_3$P, DMMP) that is simulant gas of nerve gas. Sensing materials were Sn $O_2$ added a-Al$_2$ $O_3$ with 0∼20wt.% and were physically mixed each material. They were deposited by screen printing method on alumina substrate. The sensor device was consisted of sensing electrode with interdigit(IDT) type in front and a heater in back side. Total size of device was 7${\times}$10${\times}$0.6㎣. Crystallite size & phase identification and morphology of fabricated Sn $O_2$ powders were analyzed by X-ray diffraction and by a scanning electron microscope, respectively. Fabricated sensor was measured as flow type and resistance change of sensing material was monitored as real time using LabVIEW program. The best sensitivity was 75% at adding 4wt.% $\alpha$-Al$_2$ $O_3$, operating temperature 30$0^{\circ}C$ to DMMP 0.5ppm. Response and recovery time were about 1 and 3min., respectively. Repetition measurement was very good with $\pm$3％ in full scale.TEX>$\pm$3％ in full scale.

• Wind and Structures
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• v.2 no.1
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• pp.25-40
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• 1999

In this paper, artificial neural networks, a new kind of intelligent method, are employed to model and predict amplitude dependent damping in buildings based on our full-scale measurements of buildings. The modelling method and procedure using neural networks to model the damping are studied. Comparative analysis of different neural network models of damping, which includes multi-layer perception network (MLP), recurrent neural network, and general regression neural network (GRNN), is performed and discussed in detail. The performances of the models are evaluated and discussed by tests and predictions including self-test, "one-lag" prediction and "multi-lag" prediction of the damping values at high amplitude levels. The established models of damping are used to predict the damping in the following three ways : (1) the model is established by part of the data measured from one building and is used to predict the another part of damping values which are always difficult to obtain from field measurements : the values at the high amplitude level. (2) The model is established by the damping data measured from one building and is used to predict the variation curve of damping for another building. And (3) the model is established by the data measured from more than one buildings and is used to predict the variation curve of damping for another building. The prediction results are discussed.

• Journal of the Korean Geophysical Society
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• v.9 no.2
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• pp.113-120
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• 2006

A lot of small-scale reservoirs that is extravagant in whole country are controlled state or real conditionthat correct data about the practice contents is not equipped all up to now. In this study, YungNam districts that region Gyeong-Ju city reservoir is distributed much of when flow speedily choose 23 peace among 73 small scale reservoir and experimented. Acquired data every 5 seconds, and user E/S and user value TS for orthocenter to 1 second interval and executes present ondition measurement using RTK-GPS. Could was wave and state that reservoir of 15 places (about 65%) gives protective care that do 3D modelling with acquired data, and now correct contents about reservoir state past through comparative analysis with data. Also, area of full water and wave that analyze effective storage and area of full water of 23 places reservoir could know that 20.63%, effective storage decreased as 3.34%. I wish to contribute about analysis about present reservoir state through this and method the adminstration direction.

• Journal of Korean Society of Rural Planning
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• v.14 no.2
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• pp.43-54
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• 2008

As almost community facilities in korean rural village have being showed signs of decrepitude, and have a lot of problems on scale and function, it hasn't made full use of almost community facilities. To resolve these problems, it is time to make different plan considered of elements, scale and function in community facilities. In this study, after being researched the present condition and interviewed local residents on target 25 administrative districts, it was sought diverse problems about community facilities and researched satisfaction measurement, activity of local residents. With Being based on this, we also drove from essential element about community facilities in korean rural village and sorted problems of community facilities as general disposition-structure-outdoor facilities-behavioral use. Therefore, it was applied to study area and ascertained the existence of problem. Thus, we found out the improving way for appropriate community facilities in korean rural village. It will be useful to make different plan for community facilities in korean rural village.

• Wind and Structures
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• v.20 no.3
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• pp.469-488
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• 2015

A full-scale instrumented low-rise building with gable roof was built at a coastal site with a high incidence of tropical cyclones for monitoring of wind effects on the building during windstorms. This paper presents the field measurements of the wind velocity field around and the wind-induced pressures on the low-rise building during the passage of severe tropical storm Soudelor. Near-ground wind characteristics such as wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and wind velocity spectra were investigated. The wind-induced pressures on the roof of the building were analyzed and discussed. The results revealed that the eave and ridge edges on the roof were subjected to the most severe suction pressures under quartering winds. These suction pressures showed obvious non-Gaussian behavior. The measured results were compared with the provisions of ASCE 7-10 to assess the suitability of the code of practice for the wind-resistant design of low-rise buildings under tropical cyclones. The field study aims to provide useful information that can enhance our understanding of the extreme wind effects on low-rise buildings in an effort to reduce tropical cyclone wind damages to residential buildings.